Polymerizable composition and dental material

ABSTRACT

The present invention provides a polymerizable composition that is suitably used as a temporary cement for implant use and a mobile tooth-fixing material. The present invention is a polymerizable composition that includes an acrylic block copolymer (a) having at least one polymer block A that mainly contains a (meth)acrylic acid ester unit and that functions as a hard segment and at least one polymer block B that mainly contains an acrylic acid ester unit and that functions as a soft segment, a polymerizable monomer (b), and a polymerization initiator (c).

TECHNICAL FIELD

The present invention relates to a polymerizable composition that issuitable for application to biological tissues, particularly suitable asa temporary cement for implant use and a mobile tooth-fixing material,and relates to a dental material using the polymerizable composition.

BACKGROUND ART

Adhesive materials or filling materials are used for restorativetreatment of teeth, bones, etc. Polymerizable compositions containing apolymerizable monomer, a polymerization initiator, a filler, etc., aregenerally used as such adhesive materials or filling materials.Polymerizable compositions for restorative treatment of teeth, bones,etc., can be roughly classified into two types depending on the hardnessafter curing. One type is a soft material, a cured product of which isflexible, to be used as an adhesive material, a shock absorber, etc.,with respect to biological tissues, such as a temporary sealingmaterial, a rebase for denture base, and an artificial cartilage. Withthe recent development of dental care, there is a glowing demand for newsoft materials.

For example, dental treatment by implantation is widely used in recentyears for the patients who have lost their teeth due to aging, etc. Animplant is composed of an artificial tooth root to be embedded directlyin the jaw bone, a tooth crown to be placed thereabove, and a toothbase, called an abutment, which engages the artificial tooth root andthe tooth crown. These parts are bonded together at the time of use. Forthe bonding, a temporary cement is used, but the bonded portion isrequired to be removable because the implant occasionally needs to bedetached for maintenance such as washing. Therefore, a cured product ofthe temporary cement is required to have excellent flexibility. Thetemporary cement also is required to have appropriate viscosity andforming property before curing so as to have excellent handlingproperty. Further, it is required to have good adhesive properties withrespect to metals and ceramics.

Meanwhile, the growth of periodontal disease causes gingival recessionalso due to aging, etc., making it difficult to support teethsufficiently. As a result, the teeth become loose and lost easily. Theseloose teeth are called mobile teeth. To treat such a mobile tooth, amethod of fixing the mobile tooth to a sound tooth using a mobiletooth-fixing material is employed. The mobile tooth-fixing materialneeds to be removed after recovery, and thus is required to beremovable. It also is required not to break due to bending distortion tobe applied continuously during the fixing until recovery. For thisreason, a cured product of the mobile tooth-fixing material is requiredto have excellent flexibility. The mobile tooth-fixing material also isrequired to have appropriate viscosity and forming property beforecuring so as to have excellent handling property. Further, it also isrequired to have good adhesive properties with respect to toothstructure. Furthermore, a cured product thereof is required to haveexcellent transparency and color stability from the viewpoint of theaesthetic value.

As a method for imparting flexibility to a polymerizable composition, itis known to add an elastomer. For example, Patent Literature 1 reportsan example in which the impact resistance of a metallic color-shieldingadhesive material set for dental use is improved by addingbutadiene-methyl methacrylate-styrene copolymer powder, therebyimparting flexibility thereto. Further, Patent Literatures 2 to 4 reportexamples in which a dental composition to be used for denture base,etc., is made flexible by adding a styrene-diene block copolymerthereto, so that the stress relaxation properties and the adhesiveproperties to the denture base are improved. Further, Patent Literature5 reports an example in which the long-term coloration/discoloration andwater absorption properties of a dental coating material composition areimproved by adding a styrene-based thermoplastic elastomer or a methylmethacrylate-butyl acrylate copolymer thereto.

CITATION LIST Patent Literature

Patent Literature 1: JP 2002-226316 A

Patent Literature 2: JP 9(1997)-67223 A

Patent Literature 3: JP 10(1998)-139613 A

Patent Literature 4: JP 10(1998)-182329 A

Patent Literature 5: JP 2001-89693 A

SUMMARY OF INVENTION Technical Problem

The metallic color-shielding adhesive material set for dental use ofPatent Literature 1 has poor dispersibility and miscibility of therespective components because it contains an elastomer in powder form,and thus fails to satisfy the above-mentioned various properties such astransparency required as a temporary cement for implant use and a mobiletooth-fixing material.

In the dental compositions according to Patent Literatures 2 to 4, thestyrene-diene block copolymer and the (meth)acrylate monomer havedifferent polarities from each other, which causes a problem in theirmiscibility. Low miscibility causes adverse effects on theabove-mentioned various properties required as a temporary cement forimplant use and a mobile tooth-fixing material.

In the dental coating material composition of Patent Literature 5, inthe case of using the styrene-based thermoplastic elastomer, there is asimilar problem of miscibility with the (meth)acrylate monomer.Meanwhile, no block copolymer is exemplified as the methylmethacrylate-butyl acrylate copolymer.

It is therefore an object of the present invention to provide apolymerizable composition that is suitable as a temporary cement forimplant use and a mobile tooth-fixing material. It is another object ofthe present invention to provide a dental material using thepolymerizable composition.

Solution to Problem

The present invention that has achieved the above-mentioned objects is apolymerizable composition includes: an acrylic block copolymer (a)having at least one polymer block A that mainly contains a (meth)acrylicacid ester unit and that functions as a hard segment, and at least onepolymer block B that mainly contains an acrylic acid ester unit and thatfunctions as a soft segment; a polymerizable monomer (b); and apolymerization initiator (c).

The acrylic block copolymer (a) preferably has a molecular weightdistribution Mw/Mn of 1.0 to 1.5. The acrylic block copolymer (a) ispreferably inactive against a polymerizable group of the polymerizablemonomer (b).

The polymerizable monomer (b) is preferably a (meth)acrylatepolymerizable monomer.

The polymerizable composition of the present invention preferablyfurther contains a polymerization accelerator (d). The polymerizablecomposition of the present invention preferably further contains afiller (e).

The polymerizable composition of the present invention is suitably usedfor application to biological tissues.

The present invention also is a dental cement using the above-mentionedpolymerizable composition. This dental cement is optimally used as atemporary cement for implant use.

The present invention also is a mobile tooth-fixing material using theabove-mentioned polymerizable composition.

The present invention also is a dental composite resin using theabove-mentioned polymerizable composition.

Advantageous Effects of Invention

The polymerizable composition of the present invention has both goodviscosity and forming property at the same time before curing and thushas excellent handling property. Further, it exhibits good adhesiveproperties to tooth structure, bones, and metals. Furthermore, a curedproduct of the polymerizable composition has excellent flexibility,transparency, and color stability. Accordingly, the polymerizablecomposition of the present invention can be applied suitably tobiological tissues (such as teeth and bones, particularly teeth). Asspecific applications, the polymerizable composition of the presentinvention is optimally used as a temporary cement for implant use and amobile tooth-fixing material, and also is suitably used as a dentalcement and a dental composite resin.

DESCRIPTION OF EMBODIMENTS

The polymerizable composition of the present invention includes anacrylic block copolymer (a) having at least one polymer block A thatmainly contains a (meth)acrylic acid ester unit and that functions as ahard segment, and at least one polymer block B that mainly contains anacrylic acid ester unit and that functions as a soft segment; apolymerizable monomer (b); and a polymerization initiator (c).

Acrylic Block Copolymer (a)

The acrylic block copolymer (a) to be used in the present invention hasat least one polymer block A that mainly contains a (meth)acrylic acidester unit and that functions as a hard segment (hereinafter referredsimply as “polymer block A”), and at least one polymer block B thatmainly contains an acrylic acid ester unit and that functions as a softsegment (hereinafter referred simply as “polymer block B”). Accordingly,the acrylic block copolymer (a) functions as an elastomer.

In the present invention, the term “mainly contain” means that thecontent of the corresponding monomer unit is at least 50 wt %,preferably at least 80 wt %, more preferably at least 90 wt %, in allmonomer units (repeating units) in a polymer block.

The (meth)acrylic acid ester unit that constitutes the polymer block Ais not particularly limited, as long as the polymer block A functions asa hard segment of an elastomer. As a (meth)acrylic acid ester,methacrylic acid ester is preferable, and examples thereof includemethyl methacrylate, ethyl methacrylate, n-propyl methacrylate,isopropyl methacrylate, n-butyl methacrylate, s-butyl methacrylate,t-butyl methacrylate, isobutyl methacrylate, n-hexyl methacrylate,cyclohexyl methacrylate, isobornyl methacrylate, benzyl methacrylate,and phenyl methacrylate. Among these, methyl methacrylate, isobornylmethacrylate, and t-butyl methacrylate are preferable because the use ofthem allows the polymer block A to have high glass transitiontemperature and to exhibit high aggregation, so that a cured product ofthe polymerizable composition of the present invention exhibitsexcellent strength. The polymer block A may contain two or more types of(meth)acrylic acid ester units.

The content of the polymer block A in the acrylic block copolymer (a)preferably is within the range of 1 to 75 wt %, more preferably withinthe range of 1.5 to 60 wt %, further preferably within the range of 3 to50 wt %. When the content of the polymer block A is within the range of1 to 75 wt %, appropriate flexibility is imparted to a cured product ofthe polymerizable composition.

The acrylic acid ester unit that constitutes polymer block B is notparticularly limited, as long as the polymer block B functions as a softsegment of an elastomer. Accordingly, even in the case where the polymerblock A mainly contains an acrylic acid ester unit, this acrylic acidester unit is different from an acrylic acid ester unit that iscontained in the polymer block B as the main component. Examples of theacrylic acid ester include methyl acrylate, ethyl acrylate, n-propylacrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate,s-butyl acrylate, t-butyl acrylate, n-hexyl acrylate, cyclohexylacrylate, 2-ethylhexyl acrylate, dodecyl acrylate, lauryl acrylate,stearyl acrylate, 2-methoxyethyl acrylate, and2-(N,N-dimethylaminoethyl) acrylate. Among these, n-butyl acrylate,2-ethylhexyl acrylate are preferable because the use of them allows thepolymer block B to have low glass transition temperature, so that acured product of the polymerizable composition of the present inventionexhibits excellent flexibility. The polymer block B may contain two ormore types of acrylic acid ester units.

The content of the polymer block B in the acrylic block copolymer (a) ispreferably within the range of 25 to 99 wt %, more preferably within therange of 40 to 98.5 wt %, further preferably within the range of 50 to97 wt %. When the content of the polymer block A is within the range of25 to 99 wt %, appropriate flexibility is imparted to a cured product ofthe polymerizable composition.

Concerning the polymer block A and the polymer block B, the acrylic acidester unit that constitutes the polymer block B may be contained in thepolymer block A, and the (meth)acrylic acid ester unit that constitutesthe polymer block A may likewise be contained in the polymer block B, aslong as the effects of the present invention are not impaired. Further,other monomer units may be contained in these polymer blocks, as long asthe effects of the present invention are not impaired. Examples of suchother monomer include a (meth)acrylic acid ester having a functionalgroup such as 2-hydroxyethyl (meth)acrylate, 2-aminoethyl(meth)acrylate, glycidyl (meth)acrylate, and tetrahydrofurfuryl(meth)acrylate; a vinyl monomer having a carboxyl group such as(meth)acrylic acid, maleic acid, and maleic acid anhydride;(meth)acrylamide; an aromatic vinyl monomer such as styrene,alpha-methylstyrene, and p-methylstyrene; a conjugate diene monomer suchas butadiene and isoprene; an olefin monomer such as ethylene andpropylene; and a lactone monomer such as epsilon-caprolactone andvalerolactone.

The form of the bonding between the polymer block A and the polymerblock B in the acrylic block copolymer (a) is not limited, as long asthe polymer block A and the polymer block B are bonded to each other,and may be any one of the bonding forms selected from a straight chain,a branched chain, and a radial pattern, or a combination of two or moreof them. Among these, the polymer block A and the polymer block B arepreferably bonded in the form of a straight chain, and examples thereofinclude, when the polymer block A is referred to as “A” and the polymerblock B is referred to as “B”, a diblock copolymer represented by A-B, atriblock copolymer represented by A-B-A, a tetrablock copolymerrepresented by A-B-A-B, and a pentablock copolymer represented byA-B-A-B-A. Above all, a diblock copolymer (A-B) and a triblock copolymer(A-B-A) are preferably used, and a triblock copolymer (A-B-A) is furtherpreferably used, because of ease of producing the acrylic blockcopolymer (a) and excellent flexibility of a cured product of thepolymerizable composition.

The weight-average molecular weight (Mw) of the acrylic block copolymer(a) to be used in the present invention is preferably within the rangeof 5000 to 500000, more preferably within the range of 10000 to 200000,further preferably within the range of 30000 to 150000, in view of thesolubility of the acrylic block copolymer (a) in the polymerizablemonomer (b) and the flexibility of a cured product of the polymerizablecomposition. It should be noted that the weight-average molecular weight(Mw) herein means a weight-average molecular weight in terms ofpolystyrene as determined by gel permeation chromatography (GPC).

The molecular weight distribution (weight-average molecularweight/number-average molecular weight: Mw/Mn) of the acrylic blockcopolymer (a) to be used in the present invention is preferably 1.0 to1.5, more preferably 1.0 to 1.4, further preferably 1.0 to 1.3, becauseappropriate viscosity and forming property of the composition, and highflexibility of a cured product thereof are easily obtained.

The production method of the acrylic block copolymer (a) to be used inthe present invention is not specifically limited, as long as acopolymer that satisfies the conditions of the present invention on thechemical structure can be obtained, and a method according to knowntechniques can be employed. In order to obtain a block copolymer with anarrow molecular weight distribution, a method of subjecting monomers asa structural unit to living polymerization is employed. Livingpolymerization allows a block copolymer even with a molecular weightdistribution of 1.0 to 1.3 to be obtained. Example of the techniques forliving polymerization include a method of performing polymerizationusing an organic rare earth complex as a polymerization initiator, amethod of performing anionic polymerization in the presence of a mineralacid salt such as salts of alkali metals or alkaline earth metals usingan organic alkali metal compound as a polymerization initiator, a methodof performing anionic polymerization in the presence of anorganoaluminium compound using an organic alkali metal compound as apolymerization initiator, and a method known as Atom Transfer RadicalPolymerization (ATRP).

Among the above-mentioned production methods, the method of performinganionic polymerization in the presence of an organoaluminium compoundusing an organic alkali metal compound as a polymerization initiatorallows a block copolymer with a narrower molecular weight distributionto be produced, high polymerization rate to be obtained, and livingpolymerization to be performed under comparatively moderate temperatureconditions. Thus, the acrylic block copolymer (a) to be used in thepresent invention is preferably produced by anionic polymerization inthe presence of an organoaluminium compound using an organic alkalimetal compound as a polymerization initiator.

For example, as described in WO 2007/029783, a method of sequentiallypolymerizing the (meth)acrylic acid ester and the acrylic acid esterthat form the respective polymer blocks in the acrylic block copolymer(a), in the presence of an organolithium compound and an organoaluminiumcompound represented by the following general formula:

AlR¹R²R³

(where R¹ denotes an alkyl group that may have a substituent, an alkoxygroup that may have a substituent, or an aryloxy group that may have asubstituent, and R² and R³ each independently denote an alkyl group thatmay have a substituent, an alkoxy group that may have a substituent, oran aryloxy group that may have a substituent, or R² and R³ may becoupled together to form an arylenedioxy group that may have asubstituent), additionally using N,N,N′,N″,N″-pentamethyl diethylenetriamine or other tertiary amines; and an ether such as1,2-dimethoxyethane and a crown ether represented by 12-crown-4, on anas-needed basis, can be employed to perform the above-mentioned anionicpolymerization in the presence of an organoaluminium compound using anorganic alkali metal compound as a polymerization initiator.

Examples of the aforementioned organolithium compound that can be usedfor producing the acrylic block copolymer (a) include alkyl lithiumssuch as methyl lithium, n-butyl lithium, sec-butyl lithium, and t-butyllithium; aralkyl lithiums such as 1,1-diphenylhexyl lithium anddiphenylmethyl lithium; phenyl lithium, and trimethylsiloxylithium.

Further, examples of the organoaluminium compound represented by thegeneral formula include trimethyl aluminum, triethyl aluminum,triisobutyl aluminum, dimethyl(2,6-di-t-butyl-4-methylphenoxy)aluminum,diethyl(2,6-di-t-butyl-4-methylphenoxy)aluminum,diisobutyl(2,6-di-t-butyl-4-methylphenoxy)aluminum,methylbis(2,6-di-t-butyl-4-methylphenoxy)aluminum,ethylbis(2,6-di-t-butyl-4-methylphenoxy)aluminum, andisobutylbis(2,6-di-t-butyl-4-methylphenoxy)aluminum. Among these,isobutylbis(2,6-di-t-butyl-4-methylphenoxy)aluminum is preferably usedfrom the viewpoint of the capability of suppressing side reactionsduring polymerization and the ease of handling.

The acrylic block copolymer (a) to be used in the present invention issuitably produced by living polymerization. However, when it is used forthe polymerizable composition, the chain end of the acrylic blockcopolymer (a) is preferably terminated in order to prevent sidereactions. Accordingly, the acrylic block copolymer (a) is preferablyinactive against the polymerizable group of the polymerizable monomer(b). Being inactive against the polymerizable group means not to causeany chemical reaction such as polymerization initiation reaction andcoupling reaction with the polymerizable group.

Polymerizable Monomer (b)

As the polymerizable monomer (b) to be used for the polymerizablecomposition of the present invention, a radical polymerizable monomer issuitably used. Specific examples of the radical polymerizable monomer inthe polymerizable monomer (b) include esters, for example, ofalpha-cyanoacrylic acid, (meth)acrylic acid, alpha-halogenated acrylicacid, crotonic acid, cinnamic acid, sorbic acid, maleic acid, anditaconic acid, (meth)acrylamide, (meth)acrylamide derivatives, vinylesters, vinyl ethers, mono-N-vinyl derivatives, and styrene derivatives.As the polymerizable monomer (b), a (meth)acrylate polymerizable monomeris preferable from the viewpoint of the miscibility with the acrylicblock copolymer (a).

As an example of the polymerizable monomer (b) in the present invention,a monofunctional monomer having one polymerizable group and apolyfunctional monomer having a plurality of polymerizable groups arementioned.

Examples of the monofunctional monomer include 2-hydroxyethyl(meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl(meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl(meth)acrylate, 10-hydroxydecyl (meth)acrylate, propylene glycolmono(meth)acrylate, glycerol mono(meth)acrylate, erythritolmono(meth)acrylate, N-methylol (meth)acrylamide, N-hydroxyethyl(meth)acrylamide, N,N-(dihydroxyethyl) (meth)acrylamide, methyl(meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl(meth)acrylate, n-butyl (meth)acrylate, sec-butyl (meth)acrylate,t-butyl (meth)acrylate, isobutyl (meth)acrylate, n-hexyl (meth)acrylate,cyclohexyl (meth)acrylate, lauryl (meth) acrylate, cetyl (meth)acrylate,stearyl (meth)acrylate, isobornyl (meth)acrylate, benzyl (meth)acrylate,phenyl (meth)acrylate, 2,3-dibromopropyl (meth)acrylate,3-(meth)acryloyloxypropyltrimethoxysilane,11-(meth)acryloyloxyundecyltrimethoxysilane, and (meth)acrylamide. Oneof them may be used alone, or two or more types of them may be used incombination. Among these, methyl methacrylate, ethyl (meth)acrylate,n-butyl (meth)acrylate, sec-butyl (meth)acrylate, t-butyl(meth)acrylate, isobutyl (meth)acrylate, n-hexyl (meth)acrylate,cyclohexyl (meth)acrylate, and isobornyl (meth)acrylate are preferablebecause the miscibility with the acrylic block copolymer (a) and theflexibility of a cured product of the polymerizable composition areexcellent. Methyl methacrylate, t-butyl (meth)acrylate, and isobornylmethacrylate are further preferable because the toughness of a curedproduct of the polymerizable composition is excellent in addition.

Further, the polymerizable composition of the present invention maycontain an acidic group-containing polymerizable monomer as thepolymerizable monomer (b) since good bond strength to teeth, bones, andmetals can be obtained. Examples of such an acidic group-containingpolymerizable monomer include a radical polymerizable monomer that hasat least one acidic group such as phosphoric acid group, pyrophosphoricacid group, thiophosphoric acid group, phosphonic acid group, sulfonicacid group, and carboxylic acid group, together with a polymerizablegroup.

Examples of the polymerizable monomer having a phosphoric acid groupinclude 2-(meth)acryloyloxyethyl dihydrogen phosphate,3-(meth)acryloyloxypropyl dihydrogen phosphate, 4-(meth)acryloyloxybutyldihydrogen phosphate, 5-(meth)acryloyloxypentyl dihydrogen phosphate,6-(meth)acryloyloxyhexyl dihydrogen phosphate, 7-(meth)acryloyloxyheptyldihydrogen phosphate, 8-(meth)acryloyloxyoctyl dihydrogen phosphate,9-(meth)acryloyloxynonyl dihydrogen phosphate, 10-(meth)acryloyloxydecyldihydrogen phosphate, 11-(meth)acryloyloxyundecyl dihydrogen phosphate,12-(meth)acryloyloxydodecyl dihydrogen phosphate,16-(meth)acryloyloxyhexadecyl dihydrogen phosphate,20-(meth)acryloyloxyicosyl dihydrogen phosphate,bis[2-(meth)acryloyloxyethyl]hydrogen phosphate,bis[4-(meth)acryloyloxybutyl]hydrogen phosphate,bis[6-(meth)acryloyloxyhexyl]hydrogen phosphate,bis[8-(meth)acryloyloxyoctyl]hydrogen phosphate,bis[9-(meth)acryloyloxynonyl]hydrogen phosphate,bis[10-(meth)acryloyloxydecyl]hydrogen phosphate,1,3-di(meth)acryloyloxypropyl dihydrogen phosphate,2-(meth)acryloyloxyethylphenyl hydrogen phosphate,2-(meth)acryloyloxyethyl-2-bromoethyl hydrogen phosphate,bis[2-(meth)acryloyloxy-(1-hydroxymethyl)ethyl]hydrogen phosphate, andtheir acid chlorides, alkali metal salts, and ammonium salts. These maybe used individually, or two or more types of them may be used incombination.

Among the above-mentioned examples of the acidic group-containingpolymerizable monomer, the acidic group-containing polymerizable monomerpreferably has a phosphoric acid group or a phosphonic acid group, andmore preferably has a phosphoric acid group, because of excellentmiscibility with the acrylic block copolymer (a) and good bond strengthof the polymerizable composition to teeth, bones, and metals. Above all,the acidic group-containing polymerizable monomer preferably contains inits molecule an alkyl group or an alkylene group having 6 to 20 carbonatoms in the main chain, and it more preferably contains in its moleculean alkylene group having 8 to 12 carbon atoms in the main chain, as10-(meth)acryloyloxydecyl dihydrogen phosphate does, for example.

Examples of the polyfunctional monomer include aromatic compound-basedbifunctional polymerizable monomers, aliphatic compound-basedbifunctional polymerizable monomers, and at least trifunctionalpolymerizable monomers.

Examples of the aromatic compound-based bifunctional polymerizablemonomers include 2,2-bis((meth)acryloyloxyphenyl)propane,2,2-bis[4-(3-(meth)acryloyloxy)-2-hydroxypropoxyphenyl]propane (commonlyknown as “Bis-GMA”), 2,2-bis(4-(meth)acryloyloxyethoxyphenyl)propane,2,2-bis(4-(meth)acryloyloxypolyethoxyphenyl)propane,2,2-bis(4-(meth)acryloyloxydiethoxyphenyl)propane,2,2-bis(4-(meth)acryloyloxytetraethoxyphenyl)propane,2,2-bis(4-(meth)acryloyloxypentaethoxyphenyl)propane,2,2-bis(4-(meth)acryloyloxydipropoxyphenyl)propane,2-(4-(meth)acryloyloxydiethoxyphenyl)-2-(4-(meth)acryloyloxyethoxyphenyl)-propane,2-(4-(meth)acryloyloxydiethoxyphenyl)-2-(4-(meth)acryloyloxyditriethoxyphenyl)propane,2-(4-(meth)acryloyloxydipropoxyphenyl)-2-(4-(meth)acryloyloxytriethoxyphenyl)propane, 2,2-bis(4-(meth)acryloyloxypropoxyphenyl)propane,2,2-bis(4-(meth)acryloyloxyisopropoxyphenyl)propane, and1,4-bis(2-(meth)acryloyloxyethyl)pyromeritate. These may be usedindividually, or two or more types of them may be used in combination.Among these, 2,2-bis(4-(meth)acryloyloxypolyethoxyphenyl)propane ispreferable because the miscibility with the acrylic block copolymer (a)and the strength of a cured product of the polymerizable composition areexcellent. Particularly, a compound in which the average number of molesof added ethoxy group is 2.6 (commonly known as “D2.6E”) is preferable.

Examples of the aliphatic compound-based bifunctional polymerizablemonomers include glycerol di(meth)acrylate, ethylene glycoldi(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycoldi(meth)acrylate, propylene glycol di(meth)acrylate, butylene glycoldi(meth)acrylate, neopentyl glycol di(meth)acrylate, polyethylene glycoldi(meth)acrylate, 1,3-butanediol di(meth)acrylate, 1,4-butanedioldi(meth)acrylate, 1,6-hexanediol di(meth)acrylate,2-ethyl-1,6-hexanediol di(meth)acrylate, 1,9-nonanedioldi(meth)acrylate, 1,10-decanediol di(meth)acrylate,1,2-bis(3-methacryloyloxy-2-hydroxypropoxy)ethane, and2,2,4-trimethylhexamethylene bis(2-carbamoyloxyethyl) dimethacrylate(commonly known as “UDMA”). Among these, glycerol di(meth)acrylate,triethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate,1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate,2-ethyl-1,6-hexanediol di(meth)acrylate, 1,9-nonanedioldi(meth)acrylate, 1,10-decaneol di(meth)acrylate, and2,2,4-trimethylhexamethylene bis(2-carbamoyloxyethyl) dimethacrylate arepreferable because the miscibility with the acrylic block copolymer (a)and the handleability of the polymerizable composition to be obtainedare excellent. These may be used individually, or two or more types ofthem may be used in combination.

Examples of the at least trifunctional polymerizable monomers includetrimethylolpropane tri(meth)acrylate, trimethylolethanetri(meth)acrylate, trimethylolmethane tri(meth)acrylate, pentaerythritoltri(meth)acrylate, pentaerythritol tetra(meth)acrylate,dipentaerythritol penta(meth)acrylate,N,N-(2,2,4-trimethylhexamethylene)bis[2-(aminocarboxy)propane-1,3-diol]tetramethacrylate,and 1,7-diacryloyloxy-2,2,6,6-tetraacryloyloxymethyl-4-oxyheptane. Amongthese, trimethylolpropane tri(meth)acrylate is preferable because themiscibility with the acrylic block copolymer (a) is excellent.

One of the above-mentioned examples of the polymerizable monomer (b) maybe used alone. However, it is preferable that a bifunctionalpolymerizable monomer and a monofunctional monomer be used incombination from the viewpoint of the curability of the polymerizablecomposition and the toughness and flexibility of a cured productthereof. The ratio in the combined use of them is not specificallylimited, but the content of the bifunctional polymerizable monomer ispreferably 1 to 75 wt %, more preferably 2.5 to 50 wt %, furtherpreferably 5 to 25 wt %, when the total amount of the polymerizablemonomer (b) is taken as 100 wt %. When the content of the bifunctionalpolymerizable monomer is 75 wt % or less, the toughness of a curedproduct of the polymerizable composition is rendered high, where thecured product is less likely to break. In this description, the phrase“total amount of the polymerizable monomer (b)” means the total amountof polymerizable monomers contained in the whole composition. Forexample, when an embodiment of a two-part type composition is employedin the present invention, it means the total weight of polymerizablemonomers contained in the respective parts.

Further, the content of the acidic group-containing polymerizablemonomer is not specifically limited, but is preferably 1 to 50 wt %,more preferably 1.5 to 25 wt %, further preferably 2.5 to 15 wt %, whenthe total amount of the polymerizable monomer (b) is taken as 100 wt %.When the content of the acidic group-containing polymerizable monomer is1 wt % or more, good bond strength is obtained. Meanwhile, when thecontent of the acidic group-containing polymerizable monomer is 50 wt %or less, the miscibility of the polymerizable composition is maintainedat an appropriate level.

Regarding the amount of the acrylic block copolymer (a) and thepolymerizable monomer (b) to be used, 5 to 500 parts by weight of theacrylic block copolymer (a) is preferably used, and 10 to 250 parts byweight of the acrylic block copolymer (a) is more preferably used, withrespect to 100 parts by weight of the total amount of the polymerizablemonomer (b).

Polymerization Initiator (c)

The polymerization initiator (c) to be used in the present invention canbe selected from polymerization initiators commonly used in theindustrial field. Among them, polymerization initiators used for dentalapplications are preferably used. Particularly, a photopolymerizationinitiator (c-1) and a chemical polymerization initiator (c-2) are usedindependently or two or more of them are used appropriately incombination.

Examples of the photopolymerization initiator (c-1) include(bis)acylphosphine oxides, thioxanthones or the quaternary ammoniumsalts of thioxanthones, ketals, alpha-diketones, coumarins,anthraquinones, benzoin alkyl ether compounds, and alpha-amino ketonecompounds.

Preferably, among these photopolymerization initiators, at least oneselected from the group consisting of (bis)acylphosphine oxides andsalts thereof, and alpha-diketones is used. This makes it possible toobtain a composition that has excellent photocurability in visible andnear-ultraviolet ranges and sufficiently high photocurability regardlessof which light source among a halogen lamp, light-emitting diode (LED),and xenon lamp is used.

In the (bis)acylphosphine oxides to be used as the photopolymerizationinitiator, examples of acylphosphine oxides include2,4,6-trimethylbenzoyldiphenylphosphine oxide,2,6-dimethoxybenzoyldiphenylphosphine oxide,2,6-dichlorobenzoyldiphenylphosphine oxide,2,4,6-trimethylbenzoylmethoxyphenylphosphine oxide,2,4,6-trimethylbenzoylethoxyphenylphosphine oxide,2,3,5,6-tetramethylbenzoyldiphenylphosphine oxide, and benzoyldi-(2,6-dimethylphenyl) phosphonate. Examples of the bisacylphosphineoxides include bis-(2,6-dichlorobenzoyl)phenylphosphine oxide,bis-(2,6-dichlorobenzoyl)-2,5-dimethylphenylphosphine oxide,bis-(2,6-dichlorobenzoyl)-4-propylphenylphosphine oxide,bis-(2,6-dichlorobenzoyl)-1-naphthylphenylphosphine oxide,bis-(2,6-dimethoxybenzoyl)phenylphosphine oxide,bis-(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide,bis-(2,6-dimethoxybenzoyl)-2,5-dimethylphenylphosphine oxide,bis-(2,4,6-trimethylbenzoyl)phenylphosphine oxide,(2,5,6-trimethylbenzoyl)-2,4,4-trimethylpentylphosphine oxide,2,4,6-trimethylbenzoylphenylphosphine oxide sodium salt,2,4,6-trimethylbenzoylphenylphosphine oxide potassium salt, and2,4,6-trimethylbenzoylphenylphosphine oxide ammonium salt. In addition,the compounds disclosed in JP 2000-159621 A also can be mentioned.

Among these (bis)acylphosphine oxides,2,4,6-trimethylbenzoyldiphenylphosphine oxide,2,4,6-trimethylbenzoylmethoxyphenylphosphine oxide,bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, and2,4,6-trimethylbenzoylphenylphosphine oxide sodium salt are particularlypreferable.

Examples of the alpha-diketones to be used as the above-mentionedphotopolymerization initiator include diacetyl, dibenzyl,camphorquinone, 2,3-pentadione, 2,3-octadione, 9,10-phenanthrenquinone,4,4′-oxybenzyl, and acenaphthenequinone. Among these, camphorquinone isparticularly preferable since it has the maximum absorption wavelengthin the visible light region.

As the chemical polymerization initiator (c-2) in the polymerizationinitiator (c) to be used in the present invention, an organic peroxideis preferably used. The organic peroxide to be used as the chemicalpolymerization initiator is not particularly limited and a known one canbe used. Typical examples of the organic peroxide include ketoneperoxide, hydroperoxide, diacyl peroxide, dialkyl peroxide, peroxyketal,peroxyester, and peroxydicarbonate.

Examples of the ketone peroxide to be used as the chemicalpolymerization initiator include methyl ethyl ketone peroxide, methylisobutyl ketone peroxide, methylcyclohexanone peroxide, andcyclohexanone peroxide.

Examples of the hydroperoxide to be used as the chemical polymerizationinitiator include 2,5-dimethylhexane-2,5-dihydroperoxide,diisopropylbenzene hydroperoxide, cumene hydroperoxide, t-butylhydroperoxide, and 1,1,3,3-tetramethylbutyl hydroperoxide.

Examples of the diacyl peroxide to be used as the chemicalpolymerization initiator include acetyl peroxide, isobutyryl peroxide,benzoyl peroxide, decanoyl peroxide, 3,5,5-trimethylhexanoyl peroxide,2,4-dichlorobenzoyl peroxide, and lauroyl peroxide.

Examples of the dialkyl peroxide to be used as the chemicalpolymerization initiator include di-t-butyl peroxide, dicumyl peroxide,t-butylcumyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane,1,3-bis(t-butylperoxyisopropyl)benzene, and2,5-dimethyl-2,5-di(t-butylperoxy)-3-hexyne.

Examples of the peroxyketal to be used as the chemical polymerizationinitiator include 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane,1,1-bis(t-butylperoxy)cyclohexane, 2,2-bis(t-butylperoxy)butane,2,2-bis(t-butylperoxy)octane, and 4,4-bis(t-butylperoxy)valericacid-n-butyl ester.

Examples of the peroxyester to be used as the chemical polymerizationinitiator include alpha-cumyl peroxyneodecanoate, t-butylperoxyneodecanoate, t-butyl peroxypivalate,2,2,4-trimethylpentylperoxy-2-ethyl hexanoate, t-amylperoxy-2-ethylhexanoate, t-butyl peroxy-2-ethylhexanoate, di-t-butylperoxyisophthalate, di-t-butyl peroxyhexahydroterephthalate, t-butylperoxy-3,3,5-trimethylhexanoate, t-butyl peroxyacetate, t-butylperoxybenzoate, and t-butyl peroxymaleic acid.

Examples of the peroxydicarbonate to be used as the chemicalpolymerization initiator include di-3-methoxy peroxydicarbonate,di-2-ethylhexyl peroxydicarbonate,bis(4-t-butylcyclohexyl)peroxydicarbonate, diisopropylperoxydicarbonate, di-n-propyl peroxydicarbonate, di-2-ethoxyethylperoxydicarbonate, and diallyl peroxydicarbonate.

Among these organic peroxides, diacyl peroxide is preferably used fromthe viewpoint of the comprehensive balance of safety, storage stability,and radical generation ability, and among the examples thereof, benzoylperoxide is particularly preferably used.

The content of the polymerization initiator (c) to be used in thepresent invention is not particularly limited, but is preferably 0.001to 30 parts by weight with respect to 100 parts by weight of the totalamount of the polymerizable monomer (b) from the viewpoint of thecurability, etc., of the composition to be obtained. When the content ofthe polymerization initiator (c) is less than 0.001 part by weight,there are cases where polymerization does not proceed sufficiently andstickiness occurs. Therefore, the content thereof is more preferably atleast 0.05 part by weight, further preferably at least 0.1 part byweight. On the other hand, when the content of the polymerizationinitiator (c) exceeds 30 parts by weight in the case where thepolymerization initiator itself has low polymerization performance,precipitation from the composition may occur. Therefore, the contentthereof is more preferably 20 parts by weight or less, furtherpreferably 15 parts by weight or less, most preferably 10 parts byweight or less.

The polymerizable composition of the present invention is notspecifically limited, as long as it contains the above-mentioned acrylicblock copolymer (a), the polymerizable monomer (b), and thepolymerization initiator (c). The polymerizable composition of thepresent invention can be easily produced by a method known to thoseskilled in the art.

Polymerization Accelerator (d)

The polymerizable composition of the present invention preferablycontains a polymerization accelerator (d). Examples of thepolymerization accelerator (d) include amines, sulfinic acid and saltsthereof, sulfite, bisulfite, aldehydes, thiourea compounds,organophosphorus compounds, borate compounds, barbituric acidderivatives, triazine compounds, copper compounds, tin compounds,vanadium compounds, halogen compounds, and thiol compounds.

Amines to be used as the polymerization accelerator (d) can beclassified into aliphatic amines and aromatic amines. Examples of thealiphatic amines include: primary aliphatic amines such as n-butylamine,n-hexylamine, and n-octylamine; secondary aliphatic amines such asdiisopropylamine, dibutylamine, and N-methylethanolamine; and tertiaryaliphatic amines such as N-methyldiethanolamine, N-ethyldiethanolamine,N-n-butyldiethanolamine, N-lauryldiethanolamine, 2-(dimethylamino)ethylmethacrylate, N-methyldiethanolamine dimethacrylate,N-ethyldiethanolamine dimethacrylate, triethanolamine monomethacrylate,triethanolamine dimethacrylate, triethanolamine trimethacrylate,triethanolamine, trimethylamine, triethylamine, and tributylamine. Amongthese, tertiary aliphatic amines are preferable from the viewpoint ofthe curability and storage stability of the composition. Particularly,N-methyldiethanolamine and triethanolamine are more preferably used.

Examples of the aromatic amines includeN,N-bis(2-hydroxyethyl)-3,5-dimethylaniline,N,N-di(2-hydroxyethyl)-p-toluidine,N,N-bis(2-hydroxyethyl)-3,4-dimethylaniline,N,N-bis(2-hydroxyethyl)-4-ethylaniline,N,N-bis(2-hydroxyethyl)-4-isopropylaniline,N,N-bis(2-hydroxyethyl)-4-t-butylaniline,N,N-bis(2-hydroxyethyl)-3,5-di-isopropylaniline,N,N-bis(2-hydroxyethyl)-3,5-di-t-butylaniline, N,N-dimethylaniline,N,N-dimethyl-p-toluidine, N,N-dimethyl-m-toluidine,N,N-diethyl-p-toluidine, N,N-dimethyl-3,5-dimethylaniline,N,N-dimethyl-3,4-dimethylaniline, N,N-dimethyl-4-ethylaniline,N,N-dimethyl-4-isopropylaniline, N,N-dimethyl-4-t-butylaniline,N,N-dimethyl-3,5-di-t-butylaniline, 4-N,N-dimethylaminobenzoic acidethyl ester, 4-N,N-dimethylaminobenzoic acid methyl ester,N,N-dimethylaminobenzoic acid n-butoxyethyl ester,4-N,N-dimethylaminobenzoic acid 2-(methacryloyloxy)ethyl ester,4-N,N-dimethylaminobenzophenone, and butyl 4-dimethylaminobenzoate.Among these, at least one selected from the group consisting ofN,N-di(2-hydroxyethyl)-p-toluidine, 4-N,N-dimethylaminobenzoic acidethyl ester, N,N-dimethylaminobenzoic acid n-butoxyethyl ester, and4-N,N-dimethylaminobenzophenone is used preferably because excellentcurability can be imparted to the composition.

Examples of the sulfinic acid and salt thereof to be used as thepolymerization accelerator (d) include p-toluenesulfinic acid, sodiump-toluenesulfinate, potassium p-toluenesulfinate, lithiump-toluenesulfinate, calcium p-toluenesulfinate, benzenesulfinic acid,sodium benzenesulfinate, potassium benzenesulfinate, lithiumbenzenesulfinate, calcium benzenesulfinate,2,4,6-trimethylbenzenesulfinic acid, sodium2,4,6-trimethylbenzenesulfinate, potassium2,4,6-trimethylbenzenesulfinate, lithium2,4,6-trimethylbenzenesulfinate, calcium2,4,6-trimethylbenzenesulfinate, 2,4,6-triethylbenzenesulfinic acid,sodium 2,4,6-triethylbenzenesulfinate, potassium2,4,6-triethylbenzenesulfinate, lithium 2,4,6-triethylbenzenesulfinate,calcium 2,4,6-triethylbenzenesulfinate,2,4,6-triisopropylbenzenesulfinic acid, sodium2,4,6-triisopropylbenzenesulfinate, potassium2,4,6-triisopropylbenzenesulfinate, lithium2,4,6-triisopropylbenzenesulfinate, and calcium2,4,6-triisopropylbenzenesulfinate. Sodium benzenesulfinate, sodiump-toluenesulfinate, and sodium 2,4,6-triisopropylbenzenesulfinate areparticularly preferable.

As the sulfite and bisulfite to be used as the polymerizationaccelerator (d), sodium sulfite, potassium sulfite, calcium sulfite,ammonium sulfite, sodium bisulfite, and potassium bisulfite, forexample, can be mentioned. Among these, sodium sulfite is preferablyused from the viewpoint of curability.

Examples of the aldehydes to be used as the polymerization accelerator(d) include terephthalaldehyde and benzaldehyde derivatives. Examples ofthe benzaldehyde derivatives include dimethylaminobenzaldehyde,p-methyloxybenzaldehyde, p-ethyloxybenzaldehyde, andp-n-octyloxybenzaldehyde. Among these, p-n-octyloxybenzaldehyde ispreferably used from the viewpoint of curability.

Examples of the thiourea compounds to be used as the polymerizationaccelerator (d) include 1-(2-pyridyl)-2-thiourea, thiourea,methylthiourea, ethylthiourea, N,N′-dimethylthiourea,N,N′-diethylthiourea, N,N′-di-n-propylthiourea,N,N′-dicyclohexylthiourea, trimethylthiourea, triethylthiourea,tri-n-propylthiourea, tricyclohexylthiourea, tetramethylthiourea,tetraethylthiourea, tetra-n-propylthiourea, and tetracyclohexylthiourea.

Examples of the organophosphorus compounds to be used as thepolymerization accelerator (d) include triphenylphosphine,2-methyltriphenylphosphine, 4-methyltriphenylphosphine,2-methoxytriphenylphosphine, 4-methoxytriphenylphosphine,tri-n-butylphosphine, triisobutylphosphine, and tri-t-butylphosphine.Among these, triphenylphosphine and 2-methyltriphenylphosphine arepreferably used from the viewpoint of curability.

The content of the polymerization accelerator (d) to be used for thepresent invention is not specifically limited, but 0.001 to 30 parts byweight of the polymerization accelerator (d) is preferably containedwith respect to 100 parts by weight of the total amount of thepolymerizable monomer (b) from the viewpoint of the curability of thecomposition to be obtained. When the content of the polymerizationaccelerator (d) is less than 0.001 part by weight, there are cases wherepolymerization does not proceed sufficiently and stickiness occurs.Therefore, the content is more suitably at least 0.05 part by weight,further suitably at least 0.1 part by weight. On the other hand, whenthe content of the polymerization initiator (d) exceeds 30 parts byweight in the case where the polymerization initiator itself has lowpolymerization performance, precipitation from the composition mayoccur. Therefore, the content thereof is more preferably 20 parts byweight or less, further preferably 10 parts by weight or less.

In the present invention, the chemical polymerization initiator (c-2)and the polymerization accelerator (d) may be combined to form a redoxpolymerization initiator. In this case, the chemical polymerizationinitiator (c-2) and the polymerization accelerator (d) are stored inseparate containers from the viewpoint of storage stability.Accordingly, the dental polymerizable composition is provided as aproduct that at least includes a first part containing the chemicalpolymerization initiator (c-2) and a second part containing thepolymerization accelerator (d). Preferably, the dental polymerizablecomposition is provided as a kit to be used in the form of a two-partcomposition composed of the first part and the second part. Furtherpreferably, it is provided as a kit to be used as a two-paste type inwhich both parts are in paste form. When the composition is used as atwo-paste type, it is preferable that the respective pastes be separatedfrom each other during storage, and then immediately before the use, thetwo pastes be mixed and kneaded to allow chemical polymerization toproceed, or to allow chemical polymerization and photopolymerization toproceed in the case where a photopolymerization initiator is furthercontained therein, so as to be cured.

Filler (e)

In the polymerizable composition of the present invention, a filler (e)may be further contained in order to adjust the paste properties of thepolymerizable composition before curing, and also to enhance themechanical strength of a cured product thereof. As such a filler, anorganic filler, an inorganic filler, and an organic-inorganic compositefiller can be mentioned, for example.

As a material of the organic filler, polymethylmethacrylate,polyethylmethacrylate, methyl methacrylate-ethyl methacrylate copolymer,crosslinked polymethylmethacrylate, crosslinked polyethylmethacrylate,polyester, polyamide, polycarbonate, polyphenylene ether,polyoxymethylene, polyvinyl chloride, polystyrene, polyethylene,polypropylene, chloroprene rubber, nitrile rubber, ethylene-vinylacetate copolymer, styrene-butadiene copolymer, acrylonitrile-styrenecopolymer, and acrylonitrile-styrene-butadiene copolymer can bementioned, for example. These may be used independently or may be usedas a mixture of two or more of them. The shape of the organic filler isnot particularly limited, and the particle size of the filler to be usedcan be selected appropriately.

As a material of the inorganic filler, quartz, silica, alumina,silica-titania, silica-titania-barium oxide, silica-zirconia,silica-alumina, lanthanum glass, borosilicate glass, soda glass, bariumglass, strontium glass, glass ceramics, aluminosilicate glass, bariumboroaluminosilicate glass, strontium boroaluminosilicate glass,fluoroaluminosilicate glass, calcium fluoroaluminosilicate glass,strontium fluoroaluminosilicate glass, barium fluoroaluminosilicateglass, and strontium calcium fluoroaluminosilicate glass can bementioned, for example. Also, these can be used independently or two ormore of them may be mixed for use. The shape of the inorganic filler isnot particularly limited, and amorphous fillers, spherical fillers,etc., can be appropriately selected for use.

The inorganic filler may be used after being subjected to surfacepretreatment with a known surface-treating agent such as a silanecoupling agent, as needed, in order to adjust the miscibility with thepolymerizable monomer (b). Examples of the surface-treating agentinclude vinyltrimethoxysilane, vinyltriethoxysilane,vinyltrichlorosilane, vinyltri(beta-methoxyethoxy)silane,3-methacryloyloxypropyltrimethoxysilane,11-methacryloyloxyundecyltrimethoxysilane,3-glycidoxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, and3-aminopropyltriethoxysilane.

A known method can be used as a method for the surface treatment,without specific limitation. For example, there are a method in whichthe above-mentioned surface-treating agent is added by spraying whilevigorously stirring the inorganic filler, a method in which, after theinorganic filler and the above-mentioned surface-treating agent aredispersed or dissolved in a suitable solvent, the solvent is removed,and a method in which the alkoxy group in the above-mentionedsurface-treating agent is converted into a silanol group throughhydrolysis with an acid catalyst in an aqueous solution so as to beattached to the surface of the inorganic filler in the aqueous solution,from which water is thereafter removed. In any method, heating normallyin the range of 50 to 150° C. allows the reaction between the surface ofthe inorganic filler and the above-mentioned surface-treating agent tocomplete, thereby allowing the surface to be treated.

An organic-inorganic composite filler can be obtained by adding amonomer compound to the aforementioned inorganic filler beforehand,making it into a paste, thereafter polymerizing it, and crushing it. Asthe organic-inorganic composite filler, TMPT filler (obtained by mixingtrimethylolpropane methacrylate and silica filler, polymerizing it, andthen crushing it), for example, can be used. The shape of theorganic-inorganic composite filler is not particularly limited, and theparticle size of the filler can be appropriately selected for use.

The average particle size of the filler (e) is preferably 0.001 to 50μm, more preferably 0.001 to 10 μm, from the viewpoint of thehandleability of the polymerizable composition to be obtained and themechanical strength of a cured product thereof. In this description, theaverage particle size of the filler can be determined by an arbitrarymethod known to those skilled in the art. For example, it can bedetermined easily using a laser diffraction particle size distributionanalyzer mentioned later in Examples.

The content of the filler (e) is not specifically limited, but ispreferably 500 parts by weight or less, more preferably 250 parts byweight or less, further preferably 100 parts by weight or less, withrespect to 100 parts by weight of the total amount of the acrylic blockcopolymer (a) and the polymerizable monomer (b), from the viewpoint ofthe handleability of the polymerizable composition to be obtained andthe mechanical strength of a cured product thereof. When the content ofthe filler (e) is 500 parts by weight or less, the flexibility of acured product is maintained at a good level.

As long as the effects of the present invention are not impaired, thepolymerizable composition of the present invention may additionallycontain other polymers such as natural rubber, synthetic polyisoprenerubber, liquid polyisoprene rubber and hydrogenated products thereof,polybutadiene rubber, liquid polybutadiene rubber and hydrogenatedproducts thereof, styrene-butadiene rubber, chloroprene rubber,ethylene-propylene rubber, acrylic rubber, isoprene-isobutylene rubber,acrylonitrile-butadiene rubber, and styrene elastomer (e.g.,polystyrene-polyisoprene-polystyrene block copolymer,polystyrene-polybutadiene-polystyrene block copolymer,poly(alpha-methylstyrene)-polybutadiene-poly(alpha-methylstyrene) blockcopolymer, poly(p-methylstyrene)-polybutadiene-poly(p-methylstyrene)block copolymer, or hydrogenated products thereof), in order to improvethe properties such as flexibility and fluidity.

The polymerizable composition of the present invention may contain asoftener, as needed. Examples of the softener include petroleum-basedsofteners such as paraffin, naphthene, and aromatic process oils, andvegetable oil-based softeners such as paraffin, peanuts oil, and rosin.These softeners may be used individually, or two or more types of themmay be mixed for use. The content of the softener is not particularlylimited, as long as the object of the present invention is not impaired,but is generally 300 parts by weight or less, preferably 100 parts byweight or less, with respect to 100 parts by weight of the total amountof the acrylic block copolymer (a) and the polymerizable monomer (b).

Further, the polymerizable composition of the present invention maycontain a known additive within a range that does not reduce theperformance. Examples of the additive include a polymerizationinhibitor, an antioxidant, a pigment, a dye, an ultraviolet absorber, anorganic solvent, and a thickener.

Examples of the polymerization inhibitor include hydroquinone,hydroquinone monomethyl ether, dibutyl hydroquinone, dibutylhydroquinone monomethyl ether, t-butylcatechol,2-t-butyl-4,6-dimethylphenol, 2,6-di-t-butylphenol, and3,5-di-t-butyl-4-hydroxytoluene. The content of the polymerizationinhibitor is preferably 0.001 to 1.0 part by weight with respect to 100parts by weight of the total amount of the acrylic block copolymer (a)and the polymerizable monomer (b).

The polymerizable composition of the present invention has both goodviscosity and forming property at the same time before curing and thusis excellent in handling property. Further, it exhibits good adhesiveproperties to tooth structure, bones, and metals. Furthermore, a curedproduct of the polymerizable composition of the present invention isexcellent in flexibility, transparency, and color stability.Accordingly, the polymerizable composition of the present invention canbe used in applications that exploit such advantages, particularly, canbe applied suitably to biological tissues (such as teeth and bones,particularly teeth). As specific applications, the polymerizablecomposition of the present invention is optimally used as a temporarycement for implant use and a mobile tooth-fixing material, and also issuitably used as a dental cement and a dental composite resin.

A suitable configuration example of the dental cement is shown below.The dental cement preferably contains 5 to 500 parts by weight of theacrylic block copolymer (a), 0.05 to 15 parts by weight of thepolymerization initiator (c), and 0.05 to 20 parts by weight of thepolymerization accelerator (d), with respect to 100 parts by weight ofthe total amount of the polymerizable monomer (b), and 0 to 500 parts byweight of the filler (e), with respect to 100 parts by weight of thetotal amount of the acrylic block copolymer (a) and the polymerizablemonomer (b). It is more preferable to contain 10 to 250 parts by weightof the acrylic block copolymer (a), 0.1 to 10 parts by weight of thepolymerization initiator (c), and 0.1 to 10 parts by weight of thepolymerization accelerator (d), with respect to 100 parts by weight ofthe total amount of the polymerizable monomer (b), and 10 to 250 partsby weight of the filler (e), with respect to 100 parts by weight of thetotal amount of the acrylic block copolymer (a) and the polymerizablemonomer (b).

A suitable configuration example of the temporary cement for implant useis shown below. The temporary cement for implant use preferably contains5 to 500 parts by weight of the acrylic block copolymer (a), 0.05 to 15parts by weight of the polymerization initiator (c), and 0.05 to 20parts by weight of the polymerization accelerator (d), with respect to100 parts by weight of the total amount of the polymerizable monomer(b), and 0 to 250 parts by weight of the filler (e), with respect to 100parts by weight of the total amount of the acrylic block copolymer (a)and the polymerizable monomer (b). It is more preferable to contain 10to 250 parts by weight of the acrylic block copolymer (a), 0.1 to 10parts by weight of the polymerization initiator (c), and 0.1 to 10 partsby weight of the polymerization accelerator (d), with respect to 100parts by weight of the total amount of the polymerizable monomer (b),and 0 to 100 parts by weight of the filler (e), with respect to 100parts by weight of the total amount of the acrylic block copolymer (a)and the polymerizable monomer (b).

A suitable configuration example of the mobile tooth-fixing material isshown below. The mobile tooth-fixing material preferably contains 5 to500 parts by weight of the acrylic block copolymer (a), 0.05 to 15 partsby weight of the polymerization initiator (c), and 0.05 to 20 parts byweight of the polymerization accelerator (d), with respect to 100 partsby weight of the total amount of the polymerizable monomer (b), and 0 to250 parts by weight of the filler (e), with respect to 100 parts byweight of the total amount of the acrylic block copolymer (a) and thepolymerizable monomer (b). It is more preferable to contain 10 to 250parts by weight of the acrylic block copolymer (a), 0.1 to 10 parts byweight of the polymerization initiator (c), and 0.1 to 10 parts byweight of the polymerization accelerator (d), with respect to 100 partsby weight of the total amount of the polymerizable monomer (b), and 0 to100 parts by weight of the filler (e), with respect to 100 parts byweight of the total amount of the acrylic block copolymer (a) and thepolymerizable monomer (b).

A suitable configuration example of the dental composite resin is shownbelow. The dental composite resin preferably contains 5 to 250 parts byweight of the acrylic block copolymer (a), 0.05 to 15 parts by weight ofthe polymerization initiator (c), and 0.05 to 20 parts by weight of thepolymerization accelerator (d), with respect to 100 parts by weight ofthe total amount of the polymerizable monomer (b), and 0 to 500 parts byweight of the filler (e), with respect to 100 parts by weight of thetotal amount of the acrylic block copolymer (a) and the polymerizablemonomer (b). It is more preferable to contain 10 to 250 parts by weightof the acrylic block copolymer (a), 0.1 to 15 parts by weight of thepolymerization initiator (c), and 0.1 to 10 parts by weight of thepolymerization accelerator (d), with respect to 100 parts by weight ofthe total amount of the polymerizable monomer (b), and 50 to 250 partsby weight of the filler (e), with respect to 100 parts by weight of thetotal amount of the acrylic block copolymer (a) and the polymerizablemonomer (b).

EXAMPLES

Hereinafter, the present invention is described in detail with referenceto examples and comparative examples. However, the present invention isnot limited to these examples.

In the following reference examples, the weight-average molecularweights of sampled polymers (polymers that form each block) and theacrylic block copolymer (final polymer) were determined by gelpermeation chromatography (hereinafter, referred to as GPC) in terms ofpolystyrene. The device and conditions employed for GPC measurement wereas follows.

<Device and Conditions for GPC Measurement>

Device: GPC system “HLC-8020”, manufactured by TOSOH CORPORATIONSeparation columns: “TSKgel GMHXL”, “G4000HXL”, and “G5000HXL”,manufactured by TOSOH CORPORATION, connected in series

Eluent: Tetrahydrofuran

Flow rate of eluent: 1.0 ml/minuteDetection method: Differential refractive index (RI)

-   -   UV absorbance (Reference Example 4)

Further, in the following reference examples, the component ratio of therespective polymer blocks in the acrylic block copolymer was determinedby ¹H-NMR measurement. The device and condition employed for ¹H-NMRmeasurement were as follows.

<Device and Condition for ¹H-NMR Measurement>

Device: Nuclear magnetic resonance spectrometer “JNM-LA400”,manufactured by JEOL Ltd.Deuterated solvent: Deuterated chloroform

The acrylic block copolymer used in this example was produced asfollows.

Reference Example 1 Production of the Acrylic Block Copolymer (a)-1

(1) A three-way stopcock was attached to a 1 liter three-necked flask,the inside of which was degassed and substituted by nitrogen.Thereafter, 390 g of toluene, 1.4 ml of N,N′,N′,N″,N″-pentamethyldiethylene triamine, and 18 ml of a toluene solution containing 11 mmolof isobutylbis(2,6-di-t-butyl-4-methylphenoxy)aluminum was added theretoat room temperature, and 1.7 ml of a mixed solution of cyclohexane andn-hexane containing 2.2 mmol of sec-butyl lithium was further addedthereto. 14 ml of methyl methacrylate was added thereto, which wasallowed to react at room temperature for 1 hour. 1 g of the reactionsolution at that time was collected as Sample 1. Subsequently, theinternal temperature of the polymerization solution was cooled to −15°C., and 120 ml of n-butyl acrylate was added dropwise thereto over 6hours. After completion of addition, 1 g of the reaction solution wascollected as Sample 2. Subsequently, 14 ml of methyl methacrylate wasadded thereto, and the reaction solution was heated to room temperature,followed by stirring for about 10 hours. 1 g of methanol was added tothis reaction solution to stop the polymerization. The reaction solutionafter stopping the polymerization was poured into a large amount ofmixed solution of methanol and water (90 mass % of methanol), and thedeposited white precipitate was recovered as Sample 3.

(2) Samples 1 to 3 collected or recovered in the above-mentioned step(1) were subjected to GPC measurement and ¹H-NMR measurement by theabove-mentioned method. On the basis of the results, Mw (weight-averagemolecular weight), Mw/Mn (molecular weight distribution), and the massratio between methyl methacrylate polymer (PMMA) block and n-butylacrylate polymer (PnBA) block were determined for the polymer and theblock copolymers obtained at each polymerization step. Thus, it wasproved that: the white precipitate finally obtained in theabove-mentioned step (1) was a triblock copolymer composed ofPMMA-PnBA-PMMA; the overall Mw thereof was 85,000; the Mw/Mn was 1.13;and the ratio of the respective polymer blocks was PMMA(10 mass%)-PnBA(80 mass %)-PMMA(10 mass %), (that is, the total of PMMA was 20mass %). Further, Sample 1 was PMMA, the Mw thereof was 7,300, and theMw/Mn thereof was 1.06. Sample 2 was a diblock copolymer of PMMA-PnBA,the Mw thereof was 77,000, and the Mw/Mn thereof was 1.16.

Reference Example 2 Production of the Acrylic Block Copolymer (a)-2

(1) A three-way stopcock was attached to a 1 liter three-necked flask,the inside of which was degassed and substituted by nitrogen.Thereafter, 390 g of toluene, 1.4 ml of N,N′,N′,N″,N″-pentamethyldiethylene triamine, and 18 ml of a toluene solution containing 11 mmolof isobutylbis(2,6-di-t-butyl-4-methylphenoxy)aluminum was added theretoat room temperature, and 1.7 ml of a mixed solution of cyclohexane andn-hexane containing 2.2 mmol of sec-butyl lithium was further addedthereto. 35 ml of methyl methacrylate was added thereto, which wasallowed to react at room temperature for 1 hour. 1 g of the reactionsolution at that time was collected as Sample 1. Subsequently, theinternal temperature of the polymerization solution was cooled to −15°C., and 75 ml of n-butyl acrylate was added dropwise thereto over 5hours. After completion of addition, 1 g of the reaction solution wascollected as Sample 2. Subsequently, 35 ml of methyl methacrylate wasadded thereto, and the reaction solution was heated to room temperature,followed by stirring for about 10 hours. 1 g of methanol was added tothis reaction solution to stop the polymerization. The reaction solutionafter stopping the polymerization was poured into a large amount ofmixed solution of methanol and water (90 mass % of methanol), and thedeposited white precipitate was recovered as Sample 3.

(2) Samples 1 to 3 collected or recovered in the above-mentioned step(1) were subjected to GPC measurement and ¹H-NMR measurement by theabove-mentioned method. On the basis of the results, Mw, Mw/Mn, and themass ratio between methyl methacrylate polymer (PMMA) block and n-butylacrylate polymer (PnBA) block were determined for the polymer and theblock copolymers obtained at each polymerization step. Thus, it wasproved that: the white precipitate finally obtained in theabove-mentioned step (1) was a triblock copolymer composed ofPMMA-PnBA-PMMA; the overall Mw thereof was 85,000; the Mw/Mn was 1.03;and the ratio of the respective polymer blocks was PMMA(25 mass%)-PnBA(50 mass %)-PMMA(25 mass %), (that is, the total of PMMA was 50mass %). Further, Sample 1 was PMMA, the Mw thereof was 18,000, and theMw/Mn thereof was 1.05. Sample 2 was a diblock copolymer of PMMA-PnBA,the Mw thereof was 67,000, and the Mw/Mn thereof was 1.14.

Reference Example 3 Production of the Acrylic Block Copolymer (a)-3

(1) A three-way stopcock was attached to a 1 liter three-necked flask,the inside of which was degassed and substituted by nitrogen.Thereafter, 390 g of toluene, 0.95 ml of N,N′,N′,N″,N″-pentamethyldiethylene triamine, and 12 ml of a toluene solution containing 11 mmolof isobutylbis(2,6-di-t-butyl-4-methylphenoxy)aluminum was added theretoat room temperature, and 1.1 ml of a mixed solution of cyclohexane andn-hexane containing 2.2 mmol of sec-butyl lithium was further addedthereto. 5 ml of methyl methacrylate was added thereto, which wasallowed to react at room temperature for 1 hour. 1 g of the reactionsolution at that time was collected as Sample 1. Subsequently, theinternal temperature of the polymerization solution was cooled to −15°C., and 97 ml of n-butyl acrylate was added dropwise thereto over 5hours. After completion of addition, 1 g of methanol was added to thisreaction solution to stop the polymerization. The reaction solutionafter stopping the polymerization was poured into a large amount ofmixed solution of methanol and water (90 mass % of methanol), and thedeposited liquid white precipitate was recovered as Sample 2.

(2) Samples 1 and 2 collected or recovered in the above-mentioned step(1) were subjected to GPC measurement and ¹H-NMR measurement by theabove-mentioned method. On the basis of the results, Mw, Mw/Mn, and themass ratio between methyl methacrylate polymer (PMMA) block and n-butylacrylate polymer (PnBA) block were determined for the polymer and theblock copolymer obtained at each polymerization step. Thus, it wasproved that: the liquid white precipitate finally obtained in theabove-mentioned step (1) was a diblock copolymer composed of PMMA-PnBA;the overall Mw thereof was 125,000; the Mw/Mn was 1.06; and the ratio ofthe respective polymer blocks was PMMA(5 mass %)-PnBA(95 mass %).Further, Sample 1 was PMMA, the Mw thereof was 6,000, and the Mw/Mnthereof was 1.08.

Reference Example 4 Production of Styrene Block Copolymer 1

(1) 144 g of alpha-methylstyrene, 251 g of cyclohexane, 47.3 g of methylcyclohexane, and 6.8 g of tetrahydrofuran were added to apressure-resistant container with a stirring device the inside of whichhad been substituted by nitrogen. 15.0 ml of sec-butyl lithium (1.3 Mcyclohexane solution) was added to this mixed solution, which thereafterwas polymerized at −10° C. for 5 hours. After 3 hours from theinitiation of the polymerization, the weight-average molecular weight ofthe poly-alpha-methylstyrene (polymer block A) was 7800 and thepolymerization conversion of the alpha-methylstyrene was 90%.Subsequently, 40.5 g of butadiene was added to this reaction solution,which was stirred at −10° C. for 30 minutes, thereby polymerizingbutadiene (forming block B1). Thereafter, 1680 g of cyclohexane wasadded thereto. At this time, the polymerization conversion of thealpha-methylstyrene was 90%, and the 1,4-bond content of thepolybutadiene block (B1) determined by the ¹H-NMR measurement was 19 mol%. Next, 230 g of butadiene was further added to this reaction solution,which was polymerized at 50° C. for 2 hours. The weight-averagemolecular weight of the polybutadiene block (B2) in the block copolymer(structure: A-B1-B2) obtained by sampling at this time was 33000, andthe 1,4-bond content thereof determined by the ¹H-NMR measurement was 60mol %.

(2) Subsequently, in accordance with the method disclosed in JP2007-126527, a solution obtained by dissolving 1.2 g ofdichlorodimethylsilane in 30 ml of cyclohexane was added to thispolymerization reaction solution, which was stirred at 50° C. for 1hour. Thus, apoly(alpha-methylstyrene)-polybutadiene-poly(alpha-methylstyrene)triblock copolymer was obtained. The coupling efficiency at this time,as calculated from the UV absorption area ratio of the coupled product(poly(alpha-methylstyrene)-polybutadiene-poly(alpha-methylstyrene)triblock copolymer: A-B1-B2-X-B2-B1-A) and the unreacted block copolymer(poly(alpha-methylstyrene)-polybutadiene block copolymer: A-B1-B2) inGPC, was 97%. Further, as a result of the ¹H-NMR measurement, thecontent of alpha-methylstyrene polymer block in thepoly(alpha-methylstyrene)-polybutadiene-poly(alpha-methylstyrene)triblock copolymer was 33 wt %, and the 1,4-bond content of the entirebutadiene block (that is, block B1+B2) was 53 mol %.

(3) A Ziegler-type hydrogenation catalyst formed from nickel octylateand triethyl aluminum was added to the polymerization reaction solutionobtained by the above-mentioned step (2) under an atmosphere ofhydrogen, which was allowed to undergo a hydrogenation reaction at 80°C. for 5 hours with a hydrogen pressure of 0.8 MPa. Thereby, ahydrogenated product of thepoly(alpha-methylstyrene)-polybutadiene-poly(alpha-methylstyrene)triblock copolymer (which is hereinafter abbreviated as styrene blockcopolymer 1) was obtained. The resultant styrene block copolymer 1 wassubjected to the GPC measurement. As a result, it was proved that: themain component was a hydrogenated product of thepoly(alpha-methylstyrene)-polybutadiene-poly(alpha-methylstyrene)triblock copolymer with Mt (the peak top of the average molecularweight)=79000, Mn (the number-average molecular weight)=77000, Mw (theweight-average molecular weight)=78000, and Mw/Mn=1.03, and the contentof the coupled product as determined from the UV (254 nm) absorptionarea ratio in GPC was 97%. Further, the hydrogenation rate of thebutadiene block B composed of the block B1 and the block B2 asdetermined by the ¹H-NMR measurement was 99%.

Next, the components of the polymerizable compositions of Examples and

Comparative Examples are shown below together with abbreviations.

<Polymerizable Monomer (b)>

3G: Triethylene glycol dimethacrylateD-2.6E: 2,2-bis(4-methacryloyloxypolyethoxyphenyl)propaneTBM: t-Butyl methacrylateIBM: Isobornyl methacrylateMDP: 10-methacryloyloxydecyl dihydrogen phosphateDD: 1,10-decanediol dimethacrylate

<Photopolymerization Initiator (c-1)>

CQ: Camphorquinone

BAPO: Bis-(2,4,6-trimethylbenzoyl)phenylphosphine oxide

<Chemical Polymerization Initiator (c-2)>

BPO: Benzoyl peroxide

<Polymerization Accelerator (d)>

PDE: N,N-dimethylaminobenzoic acid ethyl esterDEPT: N,N-di(2-hydroxyethyl)-p-toluidine

TEA: Triethanolamine

TPBSS: Sodium 2,4,6-triisopropylbenzenesulfinate

<Filler (e)>

Fillers (e)-1 and (e)-2 were obtained by the following productionmethod.

Filler (e)-1: 3-methacryloyloxypropyltrimethoxysilane-treated silicapowder

Silica powder (“KE-P250”, manufactured by NIPPON SHOKUBAI CO., LTD.) wasground with a vibration ball mill. Thus, silica powder was obtained. 100g of the resultant silica powder, 0.5 g of 3-aminopropyltriethoxysilane,and 200 ml of toluene were put into a 500 ml one-necked eggplant-shapedflask, which was stirred at room temperature for 2 hours. Subsequently,toluene was distilled off under reduced pressure, residue of which wasthereafter dried under vacuum at 40° C. for 16 hours, and further driedunder vacuum at 90° C. for 3 hours. Thus,3-methacryloyloxypropyltrimethoxysilane-treated silica powder (filler(e)-1) was obtained. The average particle size of the filler (e)-1 asmeasured with a laser diffraction particle size distribution analyzer(“SALD-2100”, manufactured by SHIMADZU CORPORATION) was 2.4 μm.

Filler (e)-2: 3-methacryloyloxypropyltrimethoxysilane-treated colloidsilica powder

100 g of colloid silica powder (“Aerosil OX50”, manufactured by JapanAerosil Inc.), 0.5 g of 3-methacryloyloxypropyltrimethoxysilane, and 200ml of toluene were put into a 500 ml one-necked eggplant-shaped flask,which was stirred at room temperature for 2 hours. Subsequently, toluenewas distilled off under reduced pressure, residue of which wasthereafter dried under vacuum at 40° C. for 16 hours, and further driedunder vacuum at 90° C. for 3 hours. Thus,3-methacryloyloxypropyltrimethoxysilane-treated colloid silica powder(filler (e)-2) was obtained.

<Polymerization Inhibitor>

BHT: 3,5-di-t-butyl-4-hydroxytoluene

The viscosity and forming property of the polymerizable compositionobtained in Examples and Comparative Examples, and the flexural modulus,toughness, transparency, color stability, and adhesive properties totooth structure, metals, and ceramics of a cured product of thecomposition were measured or evaluated as follows.

Test Example 1 Viscosity

The polymerizable composition was placed on a rheometer (AR2000,manufactured by TA Instruments Japan Inc.) and the viscosity wasmeasured using a 20 mm diameter parallel plate while the temperature wasmaintained at 25° C. and the plate was rotated in a constant directionat a shearing speed of 1.0 sec⁻¹. Those having a viscosity obtained bythis measurement of 50 Pa·s or less were considered to have excessivelyhigh fluidity, while those having a viscosity of 1000 Pa·s or more wereconsidered to have no fluidity, and thus have poor handling property.

Test Example 2 Forming Property

A 3 mm diameter circle was drawn on dental mixing paper with a size oflength: 59 mm×width: 83 mm, and 0.3 g of the polymerizable compositionwas placed inside the circle. It was erected upright in a constanttemperature chamber at 35° C., and was allowed to stand still as it wasfor 3 minutes. Then, the moving distance of the polymerizablecomposition from the inside of the circle was measured. This test wasperformed 3 times, the average of the 3 measured values was taken as aflow score (mm). The greater the flow score, the more likely thepolymerizable composition to flow. Those having a flow score obtainedfrom this test of 3 mm or more were considered to have no formingproperty, and thus have poor handling property.

Test Example 3 Flexural Modulus

The flexural modulus was evaluated by the bending test in accordancewith ISO4049. That is, the polymerizable composition produced in each ofthe following examples was charged into a SUS mold (width: 2mm×thickness: 2 mm×length: 25 mm), and thereafter it was pressed fromabove and below each with a slide glass, and both sides thereof wereirradiated with light at 5 points on each side for 20 seconds, using adental visible light unit (JET LITE 3000, manufactured by MoritaCorporation). Thus, the polymerizable composition was cured. Theresultant cured product was subjected to the bending test using auniversal testing machine (autograph AG-100kNI, manufactured by SHIMADZUCORPORATION) at a cross-head speed of 2 mm/min. Thus, the flexuralmodulus was measured. In order to ensure excellent flexibility, theflexural modulus is preferably not more than 1000 MPa.

Test Example 4 Toughness

In the aforementioned flexural modulus measurement, the test wascontinued until the cured product reached the yield point or was broken.Specimens that were not broken were evaluated as ∘, and specimens thatwere broken were evaluated as x. Specimens that were not broken weredetermined to have excellent toughness, while specimens that were brokenwere determined to have low toughness and to be fragile.

Test Example 5 Transparency

The polymerizable composition was charged into a SUS mold (size: 2mm×diameter: 20 mm), and thereafter it was pressed from above and beloweach with a slide glass, and both sides thereof were irradiated withlight at 6 points on each side for 20 seconds, using a dental visiblelight unit (JET LITE 3000, manufactured by Morita Corporation). Thus,the polymerizable composition was cured. The transparency (ΔL) of theobtained cured product was measured using a spectrocolorimeter(CM-3610d, light source: D65, manufactured by KONICA MINOLTA HOLDINGS,INC.). In order to ensure high aesthetic value, the transparency (ΔL) isrequired to be at least 25.

Test Example 6 Color Stability

The specimen produced in Test example 5 was subjected to colormeasurement using a spectrocolorimeter (CM-3610d, light source: D65,manufactured by KONICA MINOLTA HOLDINGS, INC.), the result of which wastaken as the chromaticity before test. Subsequently, the specimen wasimmersed in distilled water at 70° C. for 10 days, and thereafter wassubjected to color measurement again, the result of which was taken asthe chromaticity after test. The change of the chromaticity after testfrom the chromaticity before test was evaluated as a ΔE value. The ΔEvalue is defined by the following formula. In order to ensure colorstability, the ΔE value is required to be 5 or less. The higher thecolor stability in this test, the more excellent the water resistance.

ΔE={(L*1−L*2)²+(a*1−a*2)²+(b*1−b*2)²}^(1/2),

where L*1, a*1, b*1, L*2, a*2, b*2 are values indicating thechromaticity (L*, a*, b*), as measured using a spectrocolorimeter, incolor systems of L*, a*, b*. The chromaticity (L*1, a*1, b*1) denotevalues after immersion in water at 70° C., and the chromaticity (L*2,a*2, b*2) denote values before immersion in water at 70° C.

Test Example 7 Tensile Bond Strength to Tooth Structure (BovineEnamel/Dentin)

The labial surface of a bovine mandibular incisor was ground with #80silicon carbide paper (manufactured by NIHON KENSHI CO., LTD.) underrunning water to form a flat surface of enamel or a flat surface ofdentin. Each flat surface was further ground with #1000 silicon carbidepaper (manufactured by NIHON KENSHI CO., LTD.) under running water, andthereafter water on the surface was blown off using a dental airsyringe.

An adhesive tape with a thickness of about 150 μm having a 3 mm diametercircular hole was attached to each flat surface, thereby defining anadhesive area. The following dental adhesive agent 1 was applied to theinside of the circular hole using a brush, which was left standing for30 seconds. Thereafter, it was dried with an air syringe until thefluidity of the applied dental adhesive agent 1 was lost. Subsequently,the polymerizable composition was charged into the circular hole on thesurface coated with the dental adhesive agent 1, and excess of thepolymerizable composition overflowing the circular hole was removed witha razor blade so that a smooth surface was obtained. Thereafter, thepolymerizable composition was cured by irradiation with light for 30seconds using a dental visible light unit (JET LITE 3000, manufacturedby Morita Corporation). One end (circular cross section) of a stainlesssteel cylindrical rod (diameter: 7 mm, length: 2.5 cm) was bonded to theresultant cured product in which an unpolymerized layer of thepolymerizable composition was still left, using a commercially availabledental resin cement (Panavia 21, manufactured by KURARAY MEDICAL INC.).After bonding, this sample was allowed to stand still for 30 minutes atroom temperature, which was then immersed in distilled water. 5 bondtest samples were produced in total, and all the samples immersed indistilled water were kept in a constant temperature chamber maintainedat 37° C. for 24 hours.

The tensile bond strength of the above-mentioned bond test samples wasmeasured using a universal testing machine (autograph AG-100kNI,manufactured by SHIMADZU CORPORATION) at a cross-head speed of 2 mm/min,and the average of the results was taken as the tensile bond strength.

Dental Adhesive Agent 1:

A mixture composed of

bis-GMA (2,2-bis[4-(3-methacryloyloxy- 5 parts by weight2-hydroxypropoxy)phenyl]propane) #801 (l,2-bis(3-methacryloyloxy- 25parts by weight 2-hydroxypropoxy)ethane) HEMA (2-hydroxyethylmethacrylate) 25 parts by weight MDP 10 parts by weight CQ 1.5 parts byweight BAPO 1.0 part by weight PDE 1.0 part by weight DEPT 1.5 parts byweight BHT 0.05 part by weight Distilled water 15.0 parts by weightEthanol 15.0 parts by weight

Test Example 8 Adhesive Properties to Metals

A titanium strip (Titanium 100, manufactured by SHOFU INC., titaniumcontent: at least 99.5%) with dimensions: 10 mm×thickness: 5 mm wasground with #1000 silicon carbide paper (manufactured by NIHON KENSHICO., LTD.) under running water to form a smooth surface, and thereafterwater on the surface was blown off with a dental air syringe.

The following dental adhesive agent 2 was applied to the smooth surfaceof the titanium strip, followed by air drying. Thereafter, an adhesivetape with a thickness of about 150 μm having a 5 mm diameter circularhole was attached thereto, thereby defining an adhesive area.Subsequently, the polymerizable composition was charged into thecircular hole on the surface coated with the dental adhesive agent 2,and excess of the polymerizable composition overflowing the circularhole was removed with a razor blade so that a smooth surface wasobtained. Thereafter, the polymerizable composition was cured byirradiation with light for 30 seconds using a dental visible light unit(JET LITE 3000, manufactured by Morita Corporation). One end (circularcross section) of a stainless steel cylindrical rod (diameter: 7 mm,length: 2.5 cm) was bonded to the resultant cured product in which anunpolymerized layer of the polymerizable composition was still left,using a commercially available dental resin cement (Panavia 21,manufactured by KURARAY MEDICAL INC.). After bonding, this sample wasallowed to stand still for 30 minutes at room temperature, which wasthen immersed in distilled water. 5 bond test samples were produced intotal, and all the samples immersed in distilled water were kept in aconstant temperature chamber maintained at 37° C. for 24 hours.

The tensile bond strength of the above-mentioned bond test samples wasmeasured using a universal testing machine (autograph AG-100kNI,manufactured by SHIMADZU CORPORATION) at a cross-head speed of 2 mm/min,and the average of the results was taken as the tensile bond strength.

Dental Adhesive Agent 2:

A mixture composed of

Acetone 99.0% 6-(4-vinylbenzyl-n-propyl)amino-1,3,5-triazine-2,4-dithion0.6% 10-methacryloyloxydecyl dihydrogen phosphate 0.4%

Test Example 9 Adhesive Properties to Ceramics

The above-mentioned test was conducted in the same manner as in Testexample 8 except that Titanium 100 used in Test example 8 was changed toa ceramic strip (VITA CELAY, manufactured by VITA), and the dentaladhesive agent 2 was changed to the following dental adhesive agent 3.

Dental Adhesive Agent 3:

A mixture composed of

Ethanol 95.0% 3-methacryloyloxypropyltrimethoxysilane 5.0%10-methacryloyloxydecyl dihydrogen phosphate 1.0%

Examples 1 to 16 and Comparative Examples 1 to 6 Preparation ofPolymerizable Composition

The raw materials shown in Table 1 to Table 4 were mixed at roomtemperature to prepare a paste A (and a paste B), and then theproperties thereof were investigated in accordance with the methoddescribed above in Test examples 1 to 9. Table 1 to Table 4 show theresults.

TABLE 1 Ex. Ex. Ex. Ex. Ex. Ex. Ex. Ex. Ex. Ex. Ex. 1 2 3 4 5 6 7 8 9 1011 Raw Acrylic block copolymer (a)-1 45 40 45 45 30 25 materials Acrylicblock copolymer (a)-2 30 30 10 Acrylic block copolymer (a)-3 70 60 30Styrene block copolymer 1 5 Styrene block copolymer 2 ¹⁾ 5 3G (b)-1 1510 15 15 15 10 15 15 15 10 10 D2.6E (b)-2 5 5 5 TBM (b)-3 40 25 30 30 5550 35 20 20 IBM (b)-4 25 10 15 10 10 MDP (b)-5 10 10 5 5 10 10 10 DD(b-)6 5 5 CQ (c-1)-1 1.0 0.5 0.5 1.5 1.5 1.0 0.5 0.5 BAPO (c-1)-2 2.51.0 2.0 2.0 3.0 1.5 3.0 2.0 1.5 2.0 2.0 PDE (d)-1 1.0 0.5 0.5 1.5 1.51.0 0.5 0.5 Filler (e)-1 25 10 50 Filler (e)-2 10 5.0 3.0 5.0 5.0 10 10BHT 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 PropertiesViscosity (Pa · s) 750 680 790 870 780 790 810 910 780 870 920 Formingproperty: 0 0 0 0 1 0 1 0 0 0 0 Flow score (mm) Flexural modulus (MPa)120 180 240 390 330 440 90 380 310 580 670 Toughness ∘ ∘ ∘ ∘ ∘ ∘ ∘ ∘ ∘ ∘∘ Transparency ΔL 50 48 42 35 53 39 41 34 47 38 34 Color stability ΔE1.6 1.7 1.4 1.9 1.4 1.7 2.4 2.1 1.4 1.8 1.5 Tensile bond strength to 9.58.2 10.3 11.3 9.2 9.5 7.8 8.1 9.3 8.9 8.3 bovine enamel (MPa) Tensilebond strength to 7.1 7.2 8.5 8.3 7.7 8.4 7.1 7.6 8.2 8.1 7.9 bovinedentin (MPa) Tensile bond strength to 7.3 7.2 8.6 8.9 7.4 8.2 7.2 7.78.3 7.8 7.6 titanium alloy (MPa) Tensile bond strength to 8.7 8.9 9.89.9 9.5 9.7 8.1 8.3 8.9 8.3 8.1 ceramics (MPa) ¹⁾ Styrene blockcopolymer 2: Hydrogenated product ofpolystyrene-polybutadiene-polystyrene (SEPTON8007, manufactured byKURARAY CO., LTD.)

TABLE 2 C. EX. 1 C. EX. 2 C. EX. 3 Raw Acrylic polymer 1 ²⁾ 20 materialsAcrylic copolymer 1 ³⁾ 10 3G (b)-1 15 15 15 TBM (b)-3 85 65 75 CQ (c-1)1.0 1.0 1.0 BAPO (c-1) 1.0 1.0 1.0 PDE (d)-1 1.0 1.0 1.0 Filler (e)-1 20Filler (e)-2 5 BHT 0.05 0.05 0.05 Properties Viscosity (Pa · s) 2604,800 7,300 Forming property: 18 0 0 Flow score (mm) Flexural modulus(MPa) 2,800 1,800 2,200 Toughness x x x Transparency ΔL 37 18 13 Colorstability ΔE 2.3 2.5 2.9 Tensile bond strength 2.4 2.8 2.9 to bovineenamel (MPa) Tensile bond strength 1.8 2.1 2.5 to bovine dentin (MPa)Tensile bond strength 2.1 2.3 2.2 to titanium alloy (MPa) Tensile bondstrength 2.5 2.3 2.6 to ceramics (MPa) ²⁾ Acrylic polymer 1:Polybutylmethacrylate (Hi Pearl M-6003, manufactured by Negami chemicalindustrial co., ltd, molecular weight: 250,000 to 350,000) ³⁾ Acryliccopolymer 1: Poly(methyl methacrylate/ethyl methacrylate) (Hi PearlM-4501, manufactured by Negami chemical industrial co., ltd, molecularweight: 650,000 to 1,000,000)

TABLE 3 EX. 12 EX. 13 EX. 14 EX. 15 EX. 16 EX. 17 EX. 18 A B A B A B A BA B A B A B Raw Acrylic block copolymer (a)-1 45 45 40 40 materialsAcrylic block copolymer (a)-2 30 30 30 30 20 Acrylic block copolymer(a)-3 70 70 60 60 70 3G (b)-1 15 15 15 15 15 15 15 10 15 15 20 20 15 5D2.6E (b)-2 5 10 10 10 15 TBM (b)-3 40 40 25 25 55 55 45 55 55 IBM (b)-410 20 5 5 5 10 10 MDP (b)-5 10 10 15 10 CQ (c-1)-1 0.25 0.25 0.5 0.250.5 BAPO (c-1)-2 2.5 1.5 1.5 1.5 1.0 1.5 2.0 BPO (c-2) 1.5 2.0 1.5 2.01.5 3.0 2.5 PDE (d)-1 0.5 0.5 0.5 0.25 0.5 DEPT (d)-2 1.0 1.5 1.0 1.51.0 1.0 1.5 TEA (d)-3 0.1 0.25 0.5 0.1 0.1 TPBSS (d)-4 0.1 0.25 0.5 0.10.1 Filler (e)-1 25 15 20 10 25 20 Filler (e)-2 5 5 3 3 5 5 5 5 BHT 0.50.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Properties Viscosity(Pa · s) 760 860 870 930 790 920 810 Forming property: 0 0 0 0 0 0 0Flow score (mm) Flexural modulus (MPa) 150 320 290 420 110 190 260Toughness ∘ ∘ ∘ ∘ ∘ ∘ ∘ Transparency ΔL 50 36 51 41 42 30 38 Colorstability ΔE 2.5 2.7 2.3 2.4 2.9 2.7 2.8 Tensile bond strength to 9.811.5 9.3 10.3 8.1 9.1 9.2 bovine enamel (MPa) Tensile bond strength to8.1 8.4 8.1 8.9 8.0 8.8 8.7 bovine dentin (MPa) Tensile bond strength to8.6 8.8 7.7 9.1 8.2 8.9 8.6 titanium alloy (MPa) Tensile bond strengthto 9.3 9.8 8.6 10.3 9.4 9.8 9.7 ceramics (MPa)

TABLE 4 EX. 12 EX. 13 EX. 14 EX. 15 EX. 16 A B A B A B A B A B RawAcrylic block copolymer (a)-1 45 25 45 25 materials Acrylic polymer 1 ²⁾20 20 Acrylic copolymer ³⁾ 10 10 Styrene block copolymer 1 5 Styreneblock copolymer 2 ¹⁾ 5 3G (b)-1 15 15 15 10 15 15 15 15 15 15 TBM (b)-340 25 40 25 85 85 65 65 75 75 IBM (b)-4 20 25 DD (b-)6 10 5 CQ (c-1)-10.25 0.25 0.25 BAPO (c-1)-2 2.5 2.5 1.5 1.5 1.5 BPO (c-2) 1.5 1.5 1.51.5 1.5 PDE (d)-1 0.5 0.5 0.5 DEPT (d)-2 1.0 1.0 1.0 1.0 1.0 TEA (d)-30.25 0.25 0.25 TPBSS (d)-4 0.25 0.25 0.25 Filler (e)-1 20 20 20 20 20 20Filler (e)-2 5 5 5 5 5 5 5 5 BHT 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.050.05 0.05 Properties Viscosity (Pa · s) 800 920 280 5,200 7,600 Formingproperty: 0 0 14 0 0 Flow score (mm) Flexural modulus (MPa) 230 2902,900 1,310 2,400 Toughness ∘ ∘ x x x Transparency ΔL 47 45 28 19 16Color stability ΔE 2.8 2.7 2.1 2.8 3.1 Tensile bond strength to 9.0 9.32.6 3.1 2.8 bovine enamel (MPa) Tensile bond strength to 8.3 8.4 2.0 2.22.3 bovine dentin (MPa) Tensile bond strength to 8.2 8.1 2.0 2.1 2.4titanium alloy (MPa) Tensile bond strength to 9.1 9.5 2.4 2.5 2.9ceramics (MPa) ¹⁾ Refer to the note below Table 1 ²⁾ , ³⁾ Refer to thenotes below Table 2

It can be seen from the results shown in Table 1 to Table 4 that thepolymerizable composition containing an acrylic block copolymer of eachExample has appropriate viscosity and forming property and excellenthandling property before curing compared to the polymerizablecompositions containing no acrylic block copolymer of the ComparativeExamples. Further, the polymerizable composition containing an acrylicblock copolymer of each Example has low flexural modulus, and shows nobreakage, thus having excellent flexibility. Furthermore, thepolymerizable composition containing an acrylic block copolymer of eachExample has high transparency and shows less color change, resulting inexcellent aesthetic value. Moreover, the polymerizable compositioncontaining an acrylic block copolymer of each Example has adhesiveproperties to tooth structure and adhesive properties to titanium andceramics. From above, it can be seen that the polymerizable compositioncontaining an acrylic block copolymer according to the present inventioncan be suitably applied to biological tissues and is optimally used as atemporary cement for implant use and a mobile tooth-fixing material.

INDUSTRIAL APPLICABILITY

The polymerizable composition of the present invention can be suitablyapplied to biological tissues (such as teeth and bones, particularlyteeth). Specifically, it is optimally used as a temporary cement forimplant use and a mobile tooth-fixing material. It also can be suitablyused as a dental cement and a dental composite resin.

1. A polymerizable composition comprising: an acrylic block copolymer(a) having at least one polymer block A that mainly contains a(meth)acrylic acid ester unit and that functions as a hard segment, andat least one polymer block B that mainly contains an acrylic acid esterunit and that functions as a soft segment; a polymerizable monomer (b),and a polymerization initiator (c), wherein the acrylic block copolymer(a) has a molecular weight distribution Mw/Mn of 1.0 to 1.5, the acrylicblock copolymer (a) is inactive against a polymerizable group of thepolymerizable monomer (b), and polymerization initiator (c) comprises achemical polymerization initiator (c-2).
 2. The polymerizablecomposition according to claim 1, wherein the acrylic block copolymer(a) has a molecular weight distribution Mw/Mn of 1.0 to 1.3. 3.(canceled)
 4. The polymerizable composition according to claim 1,wherein the polymerizable monomer (b) is a (meth)acrylate polymerizablemonomer.
 5. The polymerizable composition according to claim 1, furthercomprising: a polymerization accelerator (d).
 6. The polymerizablecomposition according to claim 1, further comprising: a filler (e). 7.The polymerizable composition according to claim 1, being used forapplication to biological tissues.
 8. A dental cement comprising thepolymerizable composition according to claim
 1. 9. The dental cementaccording to claim 8, wherein the dental cement is a temporary cementfor implant use.
 10. A dental mobile tooth-fixing material comprisingthe polymerizable composition according to claim
 1. 11. A dentalcomposite resin comprising the polymerizable composition according toclaim
 1. 12. The polymerizable composition according to claim 1, whereinsaid chemical polymerization initiator (c-2) is at least one selectedfrom the group consisting of ketone peroxide, hydroperoxide, diacylperoxide, dialkyl peroxide, peroxyketal, peroxyester, andperoxydicarbonate.